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Converting solar energy to hydrogen fuel, with help from photosynthesis – Phys.org

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Global economic growth comes with increasing demand for energy, but stepping up energy production can be challenging. Recently, scientists have achieved record efficiency for solar-to-fuel conversion, and now they want to incorporate the machinery of photosynthesis to push it further. The researchers will present their results today at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo.

“We want to fabricate a photocatalytic system that uses sunlight to drive chemical reactions of environmental importance,” says Lilac Amirav, Ph.D., the project’s principal investigator.

Specifically, her group at the Israel Institute of Technology is designing a photocatalyst that can break down water into . “When we place our rod-shaped nanoparticles in water and shine light on them, they generate positive and negative electric charges,” Amirav says. “The water molecules break; the negative charges produce hydrogen (reduction), and the positive charges produce oxygen (oxidation). The two reactions, involving the positive and negative charges, must take place simultaneously. Without taking advantage of the positive charges, the negative charges cannot be routed to produce the desired hydrogen.”

If the positive and negative charges, which are attracted to one another, manage to recombine, they cancel each other, and the energy is lost. So, to make sure the charges are far enough apart, the team has built unique heterostructures comprised of a combination of different semiconductors, together with metal and metal oxide catalysts. Using a model system, they studied the reduction and oxidation reactions separately and altered the heterostructure to optimize fuel production.

In 2016, the team designed a heterostructure with a spherical cadmium-selenide quantum dot embedded within a rod-shaped piece of cadmium sulfide. A platinum metallic particle was located at the tip. The cadmium-selenide particle attracted positive charges, while negative charges accumulated on the tip. “By adjusting the size of the quantum dot and the length of the rod, as well as other parameters, we achieved 100% conversion of sunlight to hydrogen from water reduction,” Amirav says. A single photocatalyst nanoparticle can produce 360,000 molecules of hydrogen per hour, she notes.

The group published their results in the ACS journal Nano Letters. But in these experiments, they studied only half of the reaction (the reduction). For proper function, the photocatalytic system must support both reduction and oxidation reactions. “We were not converting into fuel yet,” Amirav says. “We still needed an oxidation reaction that would continually provide electrons to the quantum dot.” The water oxidation reaction occurs in a multi-step process, and as a result remains a significant challenge. In addition, its byproducts seem to compromise the stability of the semiconductor.

Together with collaborators, the group explored a new approach—looking for different compounds that could be oxidized in lieu of water—which led them to benzylamine. The researchers found that they could produce hydrogen from water, while simultaneously transforming benzylamine to benzaldehyde. “With this research, we have transformed the process from photocatalysis to photosynthesis, that is, genuine conversion of solar energy into fuel,” Amirav says. The photocatalytic system performs true conversion of solar power into storable chemical bonds, with a maximum of 4.2% solar-to-chemical energy conversion efficiency. “This figure establishes a new world record in the field of photocatalysis, and doubles the previous record,” she notes. “The U.S. Department of Energy defined 5-10% as the ‘practical feasibility threshold’ for generating hydrogen through photocatalysis. Hence, we are on the doorstep of economically viable solar-to-hydrogen conversion.”

These impressive results have motivated the researchers to see if there are other compounds with high solar-to-chemical conversions. To do so, the team is using artificial intelligence. Through a collaboration, the researchers are developing an algorithm to search chemical structures for an ideal fuel-producing compound. In addition, they are investigating ways to improve their photosystem, and one way might be to draw inspiration from nature. A in plant cell membranes that comprises the electrical circuitry of photosynthesis was successfully combined with nanoparticles. Amirav says that this artificial system so far has proven fruitful, supporting oxidation while providing photocurrent than is 100 times larger than that produced by other similar systems.


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Abstract

The solar-driven photocatalytic splitting of water into hydrogen and oxygen is a potential source of clean and renewable fuel. However, four decades of global research have proven this multi-step reaction to be highly challenging. Here, I will present our strategies, and most recent results, in taking photocatalyst production to new and unexplored frontiers, while exploring solar to chemical conversion that goes beyond water splitting. I will focus on unique design of innovative nano scale particles, which harness nano phenomena for improved activity, and methodologies for the construction of sophisticated heterostructures. I will share our design rules and accumulated insights, which enabled us to demonstrate efficient, and stable, full-cycle endothermic redox transformations, realizing a genuine solar-to-fuel energy conversion, with state of the art efficiencies of up to 4.2%.

Citation:
Converting solar energy to hydrogen fuel, with help from photosynthesis (2020, August 17)
retrieved 17 August 2020
from https://phys.org/news/2020-08-solar-energy-hydrogen-fuel-photosynthesis.html

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New Shark Research Tracks Movements of Smooth Hammerheads – DivePhotoGuide.com

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By Ian Bongso-Seldrup, September 21, 2020 @ 02:00 AM (EST)
Source: Science Daily

With overfishing driving many hammerhead species closer to the brink of extinction, a team of researchers has been focusing on determining the migration patterns of smooth hammerhead sharks (Sphyrna zygaena) in the western Atlantic Ocean in an effort to identify areas and times for management action to help in building back the depleted species.

The team tagged juvenile hammerheads off the US Mid-Atlantic coast using fin-mounted satellite tags and tracked the animals for up to 15 months. The tags reported the sharks’ movement patterns in near real time via a satellite link to the researchers.

“Getting long-term tracks was instrumental in identifying not only clear seasonal travel patterns, but importantly, also the times and areas where the sharks were resident in between their migrations,” said Ryan Logan, first author of the paper published in Frontiers in Marine Science. Logan is a PhD student at Nova Southeastern University’s Guy Harvey Research Institute and SOSF SRC and the Save Our Seas Foundation Shark Research Center (SOSF SRC).

Logan and his coworkers found that the sharks migrate between two seasonally resident areas: coastal waters off New York in the summer and off North Carolina in the winter. Identifying these habitats is vital for ultimately designating the areas as “Essential Fish Habitat”—with the accompanying limitations on fishing and development.

The high-resolution data also revealed that the hammerheads spent a lot of time in the Mid-Atlantic Shark Area (MASA) in the winter, starting in December. The MASA zone is closed to bottom longline fishing between January 1st and July 31st to protect dusky sharks, so beginning the closure of the zone in December would further reduce the fishing mortality of juvenile smooth hammerheads.   

Check out the tracks of various shark species, including smooth hammerheads, at Guy Harvey Research Institute’s dedicated website.

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Venus is a Russian planet — say the Russians – CNN Philippines

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(CNN)— No longer confined to territories here on Earth, Russia has now staked its claim on Venus, saying it is a “Russian planet.”

This week, Dmitry Rogozin, head of the Russian space corporation Roscosmos, revealed that the country plans to send its own mission to Venus in addition to “Venera-D,” the planned joint mission with the US, the Russian state news agency TASS reported.

Rogozin was addressing reporters at the HeliRussia 2020 exhibition, an international expo of the helicopter industry in Moscow.

“Resuming Venus exploration is on our agenda,” he told reporters Tuesday.

“We think that Venus is a Russian planet, so we shouldn’t lag behind,” he said.

“Projects of Venus missions are included in the united government program of Russia’s space exploration for 2021-2030.”

The statement came the day after scientists revealed that a gas on Earth called phosphine had also been detected in the atmosphere of Venus.

Venus is similar in size to Earth and is our closest planetary neighbor, but it spins backward compared to other planets.

The study authored by Cardiff University professor Jane Greaves and her colleagues was published Monday in the journal Nature Astronomy.

The discovery of phosphine on Venus elevates it to an area of interest worth exploring in our solar system alongside the ranks of Mars and “water world” moons like Enceladus and Europa, Seager said.

“Our hoped-for impact in the planetary science community is to stimulate more research on Venus itself, research on the possibilities of life in Venus’ atmosphere, and even space missions focused to find signs of life or even life itself in the Venusian atmosphere,” Seager said.

According to the European Space Agency, the Russians do have significant experience when it comes to Venus.

Its website states: “Between 1967-1984 Venusian studies carried out in Russia were at the forefront of international research into this planet.

“Since then, Russia has still preserved its unique expertise in designing and developing landing craft for Venus and continues to define scientific tasks for those craft.”

This story was first published on CNN.com, “Venus is a Russian planet — say the Russians.”

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Florida man survives alligator attack while walking dog, gets 65 stitches – FOX 5 Atlanta

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Florida man out walking his dog was attacked by an alligator and nearly dragged into a canal behind his home.

Mark Johnson, 61, said he was walking along the canal last Sunday in Port. St. Lucie with his 8-year-old golden retriever when he saw a gator turn towards them.

Johnson said his foot got stuck in mud moments before he saw “the lunge” as the alligator grabbed his leg.

HURRICANE SALLY: MASSIVE ALLIGATOR CAPTURED SWIMMING IN ALABAMA STORM SURGE

“He starts clamping down pretty tight, and he started to pull, and the next thing I do … I poke [the gator] through the eye,” he told WPLG-TV.

Johnson told Treasure Coast Newspapers that after he stuck his finger in the gator’s eye, the reptile immediately let go and swam away.

After limping home with blood dripping from his leg, Johnson’s wife cleaned the wound and wrapped the leg in a towel before taking him to a hospital.

Johnson said he suffered 12 puncture wounds that required 60 stitches, plus another five to mend the index finger that was cut on the gator’s eye socket.

The Florida Fish and Wildlife Conservation Commission said a trapper captured the gator involved in the attack on Wednesday.

AUSTRALIAN RANGERS TRAP 770-POUND CROCODILE NEAR OUTBACK TOURIST SPOT

Officials said the alligator measured 8 feet, 6 inches and weighed nearly 250 pounds. The reptile has since been relocated to an alligator farm.

Johnson said that even though the reptile was trying to drag him into the water, staying calm was what helped him survive.

“You cannot panic,” he told the paper. “I bass fish all the time, too. I’ll reach down and lift up the bass with my hand. I just got lucky.”

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Johnson said when he’s able to walk his dog again, he’ll probably carry some sort of weapon for protection.

The Associated Press contributed to this report.

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